Rising Sumatran tiger numbers show impact of protection efforts

The numbers of Sumatran tigers in the Bukit Barisan Selatan National Park rose significantly over the decade to 2015. Source: Steve Wilson / Shutterstock

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A NEW scientific paper has highlighted rising numbers of critically endangered tigers in a national park on Indonesia’s Sumatra island as the result of establishing an Intensive Protection Zone.

Authored by researchers from the Wildlife Conservation Society (WCS) and Bukit Barisan Selatan National Park Authority, the paper demonstrates numbers of Sumatran tigers in the park rose significantly over the decade to 2015, despite being on the Unesco List of World Heritage in Danger list.

“This increasing population trend in Sumatran tigers is a dream come true for all conservationists in Indonesia,” said Dr Noviar Andayani, WCS-Indonesia country director and co-author of the paper, which was published in Oryx – The International Journal of Conservation.

The Panthera tigris sumatrae is the only remaining species of “island tigers”, a subspecies including the now-extinct Java and Bali tigers. Tigers in Indonesia are at risk of habitat loss, a depleted prey base, conflict with human beings, and being poached for their bones, skin and other body parts.

The number of wild tigers in Asia has declined by an estimated 50 percent since 1998. In Bukit Barisan Selatan National Park, however, Sumatran tiger population density numbers increased from 1.6 tigers per 100 square kilometres in 2002 to 2.8 tigers by 2015, shows the research.

“This ratio indicates that the tiger population in the National Park is in a healthy condition and breeding opportunity exists for many females within the areas we surveyed,” said lead author and WCS Species Conservation Specialist Wulan Pusparini.

Researchers placed more than 120 cameras over an expanse of 1,000 kilometres squared within the park’s dedicated Intensive Protection Zone. “Our study not only looks at population condition, but also used the photographs to assess the threat of people illegally entering the park,” said Wulan.

Bukit Barisan National Park. Source: Indonesia Tourism

Some 77 incidents of illegal entrances were recorded over a period of six months, 20 percent of which involved armed poachers. The paper even notes that a “large number” of cameras were stolen from the park, indicating a “high level of illegal activity” in the forest.

“The tiger population increase can’t be separated from our efforts to maintain this area through ranger patrols,” said then-head of Bukit Barisan National Park and one of the co-authors, Timbul Batubara.

The researchers thus recommend stepping up the level of law enforcement to prevent poaching of tigers and illegal logging, based upon success at a comparable World Heritage Site in Thailand.

Along with Kerinci Seblat National Park and Gunung Leuser National Park, Bukit Barisan Selatan is classified as Unesco Tropical Heritage of Sumatra. In 2011, the UN body added the park to its World Heritage list in Danger. It is also home to two more of the world’s most endangered species: the Sumatran elephant and Sumatran rhino.

“With support from WCS and other partners, we conducted patrols in and around the park to remove tiger and prey snare traps and prevent habitat encroachment,” said Timbul.

WCS-Indonesia hopes to “ensure that in the coming years, the Unesco Tropical Heritage of Sumatra can be removed from the ‘in danger list’,” added Noviar.